The comments made me worry, but I managed to beat her in one try.

Though I was level 100 and using the Easy Mode build (Motivity, Wrench Baton, Puppet String)

This boss is 100% weak to acid not fire, its a human type. also this boss is cancer on NG+ one shot disruption with lada cartridge is crazy

Easy Mode for the Boss: Dodge to the Side instead of Blocking. Try it 2-3 time and you got the Moveset, Blocking is Dying with this Boss

this is literally the most cancerous part of the game

Locking Miss Megamind in place by climbing partway down the ladder and chucking all your throwables at her still works. I shot her once with falcon eyes and climbed back down, but only to about the halfway point of the ladder. You need to quickly climb back up BEFORE she reaches her reset point in the middle of the room. Poke her again with falcon eyes just to be sure it worked and that she doesn't re-aggro you, and then pelt her with everything you have. Happy cheesin'.